1. Field of the Invention
The present invention relates to a railway car or a monorail car in which a vacuum insulating material and a sound absorbing material are used.
2. Description of the Related Art
In recent years, car bodies using large-size hollow molded materials made of light metal (of double skin construction) have been fabricated from the standpoint of weight saving and pressure tightness improvement which result from the rationalization of fabrication and high speed design. In order to save weight and improve pressure tightness, these car bodies are constructed so that their side portions and roof shell structures have curved surfaces. For example, such a shell structure is observed in a car described in the Japanese Patent Laid-Open Publication No. 10-258736.
The current mainstream of a heat insulating structure used in such a carbody shell structure is such that the entry of heat from outside a carbody is prevented by sticking a fibrous heat insulating material, such as glass wool, between the in-car side of a carbody shell structure and an outfitting lining. However, if such a structure is applied to a double skin shell structure, the thickness of a wall increases and especially in railroad cars, it is required to reduce the thickness as far as possible from the standpoint of ensuring an in-car space. For this reason, materials excellent in heat insulating performance have been used. To meet these requirements, carbody structures using vacuum insulating materials as those described in the Japanese Patent Laid-Open Publication No. 10-258736 and the Japanese Patent Laid-Open Publication No. 11-100915 have been investigated.
A method of reducing in-car noise by imparting vibration damping performance to a structure of railroad car is described in “Vehicular Technology,” December 2001/9, No. 222, pp. 22-31. Although it can be expected that this method is effective in reducing noise, the thickness of a heat insulating material for obtaining heat insulating properties becomes large and this poses a problem in ensuring a wide in-car space.
In the above-described conventional technique, in attaching a vacuum insulating material to a carbody shell structure, a large force is locally applied to a core material of the vacuum insulating material when the vacuum insulating material is directly pressed against the surface of the carbody shell structure, with the result that the core material is deformed and that an outer container of the heat insulating material is broken. This poses the problem that airtightness is lost and heat insulating performance decreases.
There has been proposed a method in which by use of a rail portion on the in-car side, the surface of a vacuum insulating material is pressed and fixed by a spring material of steel sheet. However, because the vacuum insulating material is pressed for a long period, the outer container and the core material are deformed and sink down, and it is feared that eventually cracks would occur.
In the method of reducing in-car noise by sticking a vibration damping material to a double skin shell structure, a weight increase of the shell structure and the thickness of the heat insulating material pose a problem, and thin wall design of the heat insulating acoustical function is demanded.